The present invention provides methods in the field of cancer diagnosis. In particular, A process for the determination of CTp11 (cancer/testis-associated protein of 11kDl) and for determining whether a tumor sample has metastatic potential is provided.
In order for metastasis of cancer to occur, several hurdles must be overcome, such as degradation of the extracellular matrix and basal membrane, intra- and extravasation of vessels of the blood and of the lymphatic system, escape by the attack of the immune system, and homing and colonization of distant organs (Pardee, A. B., Advances in Cancer Res. 65 (1994) 213-227; Ponta, H., et al., Biochem. Biophys. Acta 1198 (1994) 1-10). A further level of complexity is achieved in that different types of cancers make use of different molecular mechanisms for metastasis and exhibit different tropism of metastasis.
Metastasizing and non-metastasizing human melanoma cell lines have been important tools in identifying differentially expressed genes and for investigation of their role in metastasis (Weterman, M. A. J., et al., Cancer Res. 52 (1992) 1291-1296; Weterman, M. A. J., et al., Int. J. Cancer 53 (1993) 278-284; Van Groningen, J. M., et al., Cancer Res. 55 (1995) 6237-6243; Weterman, M. A. J., et al., Int. J. Cancer 60 (1995) 73-81; van Muijen, G. N. P., et al., Int. J. Cancer 48 (1991) 85-91; van Muijen, G. N. P., et al., Clin. Ekp. Metastasis 9 (1991) 259-272).
Cell adhesion molecules play an important role in the invasion, dissemination, extravasation and lodging of tumor cells. The interaction of disseminated tumor cells with endothelium and tissue stroma is supposed to be one of the critical steps in tumor progression and metastasis formation (Ebnet, K., et al., Annu. Rev. Immunol. 14 (1996) 155-177; Varner, J. A., and Cheresh, D. A., Curr. Opin. Cell Biol. 8 (1996) 724-730; Albelda, S. M., Lab. Invest. 68 (1993) 4-17).
CTp11 is a polypeptide homologous to the polypeptide sequences described in EMBL Database AI962751, AA412605, and AA412270 as well as in SEQ ID NO:18 and SEQ ID NO:75 of WO 99/46374.
In accordance with the present invention, it was surprisingly found that a protein, termed CTp11 (cancer/testis-associated protein of 11 kD), is upregulated in metastatic cancer cells as compared to their non-metastatic counterparts. CTp11 may be involved in promotion of several steps of the metastatic cascade. CTp11 is a specific marker of metastatic cancer cells, due to the fact that it can be presented in an MHC Class I complex on cytotoxic T cells but is not presented naturally because the only non-tumor cells (testis cells) in which CTp11 is found do not present antigens in an MHC Class I context. The CTp11 gene codes for a polypeptide of SEQ ID NO:2.
The present invention provides a process for detecting the presence or absence of at least one specific nucleic acid or mixture of nucleic acids, or distinguishing between two different sequences in said sample, wherein the sample is suspected of containing said sequence or sequences, which process comprises the following steps in order:
(a) incubating said sample under stringent hybridization conditions with a nucleic acid probe which is selected from the group consisting of:
(i) a nucleic acid sequence of SEQ ID NOS: 1 and 3 to 6;
(ii) a nucleic acid sequence which is exactly complementary to a nucleic acid sequence of (i);
(iii) a nucleic acid sequence which hybridizes under stringent conditions with the sequence of (i); and
(iv) a nucleic acid sequence which hybridizes under stringent conditions with the sequence of (ii); and
(b) determining whether said hybridization has occurred.
Moreover, the present invention provides a process for determining whether or not a cancer cell-containing test sample has potential for tumor progression or metastasis, wherein the test sample and a cancer cell-containing sample which is free from metastasis and wherein both samples are obtained from the same individual or different individuals of the same species, which process comprises the following steps:
(a) incubating each respective sample under stringent hybridization conditions with a nucleic acid probe which is selected from the group consisting of:
(i) a nucleic acid sequence of SEQ ID NOS: 1 and 3 to 6;
(ii) a nucleic acid sequence which is exactly complementary to a nucleic acid sequence of (i);
(iii) a nucleic acid sequence which hybridizes under stringent conditions with the sequence of (i); and
(iv) a nucleic acid sequence which hybridizes under stringent conditions with the sequence of (ii); and
(b) determining the approximate amount of hybridization of each respective sample with said probe, and
(c) comparing the approximate amount of hybridization of the test sample to an approximate amount of hybridization of the sample which is free from metastasis, to identify whether or not the test sample contains a greater amount of the specific nucleic acid or mixture of nucleic acids than does the sample which is free from metastasis.